Bob Vila Radio: Bath Venting

The bathroom is the most humid room in your home. Tubs, showers, and sinks all produce moisture, which can lead to peeling paint, unsightly stains, and the growth of mold and mildew. Your best defense is an effective ventilation fan, which removes moisture and odor and encourages the circulation of fresh air.

There are three basic types. The most common are ceiling-mounted fans, which are installed directly in the ceiling and vent into the attic or through the roof. Less prevalent are inline fans, where a grille in the bathroom connects via ductwork to a fan installed in the attic. A third option, wall-mounted fans, are (as the name implies) installed on an exterior wall and vent outside.

What size fan should you buy? Vent fan capacity is rated in CFMs, or cubic feet per minute. According to the Home Ventilating Institute, an effective bathroom vent fan should produce eight air exchanges each hour. One rule of thumb is to estimate 1 CFM per square foot of bathroom area. For example, an eight-by-ten-foot bathroom is 80 square feet, so you’d need a fan rated at least 80 CFM. If your bathroom is especially large, or if you have a whirlpool tub, you’ll probably need an even more powerful fan.

Bob Vila Radio is a newly launched daily radio spot carried on more than 75 stations around the country (and growing). You can get your daily dose here, by listening to—or reading—Bob’s 60-second home improvement radio tip of the day.